In order to determination of Cycocel application effect on barley cultivars (Hordeum vulgar L.) under different sowing date, an experiment was carried out at split factorial in randomized completely block design with three replications at Mazandaran province in 2009-2010. Main factor was sowing dates in three levels including 7 and 26 November and 11 December and sub factor was three varieties including Sahra, Productive and M12 and cycocel rates in two levels including 0 and 2.8 lit/cycocel ha. Results showed maximum and minimum of the spike per plant, grain per spike, and grain yield were obtained on 26 November and 11 December, respectively. Sahra and M12 varieties had to most and least of the spike length, tiller per plant, spike per plant, grain per spike, 1000 grain weight and grain yield, respectively. With application of the cycocel, decreased of the stem length, but increased of the spike length, tiller per plant, spike per plant, grain per spike, 1000 grain weight and grain yield. Maximum and minimum of the spike length, tiller per plant and grain yield were obtained in interaction of the 26 November × sahra cultivar and 11 December × M12 varieties. Therefore sowing date of the 26 November, sahra variety and application of the 2.8 lit/cycocel ha because of the most of increased the yield components and due to grain yield introduced the best of treatment.